Special thanks to grap3fruitman for posting the pics, and Rattleman for testing.

Instructions:Make sure only one of these codes is turned on at once.Select a level from the stage select map, and as the map begins to fade out, Hold Up (JUST UP) on the Dpad. As soon as the loading screen appears, you can let go of the Up arrow. You'll get the level you entered the code for, with the character whose level you selected on the map.